Oxidation of titanous salts



Patented Aug. 2, 1938 UNITED STATES PATENT OFFICE OXIDATION OF TITANOUSSALTS 'No Drawing. Application January 9, 1936, Serial No. 58,256

'7 Claims.

The present invention relates to the oxidation of dissolved trivalenttitanium salts by means of elemental oxygen and a catalyst, the latterbeing, particularly, copper. Titanous salt solutions such as titanouschloride or particularly titanous sulfate are, under certain conditions,relatively easy to oxidize by means of elemental oxygen or atmosphericair, for example, when the titanium content of such solutions is relatively very low and when the solutions are neutral or nearly neutral.If, however, the titanium solution is such as is produced under theusual conditions of manufacture the behavior is entirely difierent andthe titanium in the titanous state is extremely difficult to oxidize bymeans of elemental oxygen or atmospheric air.

For example, in titanium oxide manufacture the solutions of titaniumsalt prior to the hydrolysis step contain from 150 grams to 275 grams oftitanium in solution. From 99.5 per cent to 98.0 per cent of suchtitanium is in the titanic state with from 0.5 per cent to 2.0 per centin the titanous state. Furthermore, such solutions contain relativelylarge quantities of free sulfuric acid, from 150 grams to 300 grams ofHzSO4 per liter. It is under conditions such as these that the oxidationof trivalent titanium content of such solutions by means of elementaloxygen or atmospheric air is extremely diflicult and too time consumingto be practical on a commercial scale.

I found, however, that if the solution contains small amounts of acopper salt, elemental oxygen will readily oxidize trivalent titaniumcompounds to tetravalent titanium. I found, for instance, that whenatmospheric air is bubbled through strong acid solutions containingtrivalent titanium no oxidation of the trivalent titanium takes place,particularly at temperatures below C. If a, copper salt, however ispresent in the solution air will readily oxidize the trivalent titaniumto tetravalent titanium even at room temperature and as the temperatureis raised the speed with which oxidation takes place increasestremendously. The amount of copper salt needed as a catalyst in thisreaction, is very slight, and it is usually sufilcient to suspend somecopper oxide in the acid solution and very little copper is dissolved.For practical use of this reaction I prefer to carry it out at somewhatelevated temperature, as between 45 and 50 C. This type of reaction hasmany other practical applications in processes where small amounts oftrivalent titanium present in a tetravalent titanium salt solution aredesired to be oxidized, such as disclosed in an application by CarltonE. Smith, Serial No. 58,257 filed at even date herewith.

I claim:

1. In an acid process of oxidizing trivalent titanium to tetravalenttitanium the step of contacting a solution containing trivalent titaniumwith elemental oxygen in the presence of a small amtount of an addedcopper compound as a catalys 2. In a process of oxidizing trivalenttitanium to tetravalent titanium the step of bubbling air through anaqueous acid solution of trivalent titanium containing a small amount ofan added copper compound as a catalyst.

3. In a process of oxidizing the trivalent titanium in an acid solutioncontaining a major proportion of tetravalent titanium and a minorproportion of trivalent titanium, the steps of adding a small amount ofa copper compound as a catalyst to said solution and contacting saidsolution with elemental oxygen.

4. A process for oxidizing trivalent titanium to tetravalent titanium,comprising contacting a trivalent titanium containing acid solution witha gaseous oxidizing medium from the group consisting of oxygen and airin the presence of a slight amount of an added copper salt as a catalystand maintaining said solution during such contact at a temperature ofsubstantially 45-50 C.

5. A process for oxidizing trivalent titanium to tetravalent titanium,comprising adding a slight amount of a copper compound to an acidictitanium salt solution prepared for hydrolysis, and thence subjectingthe same to the oxidizing action of air.

6. A process for oxidizing trivalent titanium to tetravalent titanium,comprising introducing a gaseous oxidizing medium from the groupconsisting of oxygen and air into an acidic solution containingtrivalent titanium and a small amount of a catalytic copper compoundpreviously added to said solution.

'7. A process for oxidizing trivalent titanium to tetravalent titanium,comprising introducing a gaseous oxidizing medium from the groupconsisting of oxygen and air into an acidic solution containingtrivalent titanium and a small amount of a catalytic copper saltpreviously added to said solution.

CHARLES R. HAGER.

CERTIFICATE OF CORRECTION.

Patent 110., 2,125, L 0, August 2, 19

CHARLES R. HAGER.

It is hereby certified that error appears in the printed specificationof, the above numbered patent requiring correction as follows: Page 1,second column, line 6, claim 1,. for the words "an acidprocess read aprocess; line 8,v same claim, for "a solution" read an acid solution;and that the said Letters Patent shouldbe read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 27th day of September, A, D. 1958.

Henry Van Arsdale (Seal) I Acting Commissioner of Patents. v

